GO MF analysis revealed that the DEGs between RA and HC were significantly enriched in calcium ion binding (GO: 0005509, p-value = 0.026), carbohydrate binding (GO: 0030246, p-value = 0) and structural molecule activity (GO: 0005198, p-value = 0.004), etc. Additionally, significantly enriched KEGG pathways were mainly involved in hematopoietic cell lineage (hsa04640, p-value = 0.007), renin-angiotensin system (hsa04614, p-value = 0.010), tryptophan metabolism (hsa00380, p-value = 0.048) etc. Here, REN is linked to rheumatoid arthritis.